1. Field of the Invention
The invention relates to a connecting rod for an internal combustion engine, and to an internal combustion engine.
2. Description of the Related Art
DE 10 2010 016 037 A1 and FIG. 1 and show a connecting rod 10 of an internal combustion engine having an adjustable compression ratio. The connecting rod 10 has a crankpin bearing eye 11 and a connecting-rod bearing eye 12. The crankpin bearing eye 11 attaches the connecting rod 10 to a crankshaft (not shown in FIG. 1) and the connecting-rod bearing eye 12 attaches the connecting rod 10 to a cylinder piston (not shown in FIG. 1) of the internal combustion engine. The connecting rod 10 has an eccentric adjustment device 13 with an eccentric (not shown in FIG. 1), an eccentric lever 14 and eccentric rods 15, 16. The eccentric lever 14 has a bore that is arranged eccentrically with respect to a center point 17 of the connecting-rod bearing eye 12 and that has a center point 18. The bore in the eccentric lever 14 receives the eccentric and a bore in the eccentric receives a piston pin. The eccentric adjustment device 13 enables adjustment of an effective connecting rod length leff, where the connecting rod length is to be understood to mean the spacing of the center point 18 of the bore in the eccentric lever 14 from a center point 19 of the crankpin bearing eye 11. The eccentric rods 15, 16 can be moved to rotate the eccentric body 14 and thus change the effective connecting rod length leff. Each eccentric rod 15, 16 has a piston 20, 21 that is guided displaceably in a hydraulic chamber 22, 23. A hydraulic pressure acts exists in the hydraulic chambers 22, 23 and on the pistons 20, 21 assigned to the eccentric rods 15, 16 so that movement of the eccentric rods 15, 16 is possible or not possible depending on the amount of oil in the hydraulic chambers.
The adjustment of the eccentric adjustment device 13 is initiated by the action of inertia and load forces of the internal combustion engine that act on the eccentric adjustment device 13 during a work stroke of the internal combustion engine. The directions of action of the forces that act on the eccentric adjustment device 13 change continuously during a work stroke. The adjustment movement is assisted by the pistons 20, 21 that are loaded with hydraulic oil and act on the eccentric rods 15, 16. The pistons 20, 21 prevent a restoring movement of the eccentric adjusting device 13 on account of varying directions of the forces that act on the eccentric adjustment device 13. The eccentric rods 15, 16 that interact with the pistons 20, 21 are attached to the eccentric body 14 on both sides. The hydraulic chambers 22 and 23, in which the pistons 20, 21 are guided, can be charged with hydraulic oil from the crankpin bearing eye 11 via hydraulic oil lines 24 and 25. Check valves 26 and 27 prevent a return flow of the hydraulic oil from the hydraulic chambers 23 and 24 back into the hydraulic lines 24 and 25. A switchover valve 29 is received in a bore 28 of the connecting rod 10. The switching position of the switchover valve 29 determines which of the hydraulic chambers 22 and 23 is filled with hydraulic oil and which of the hydraulic chambers 22 and 23 is evacuated, and the adjustment direction or direction of rotation of the eccentric adjustment device 13 is dependent on this switching. The hydraulic chambers 22 and 23 are in contact via fluid lines 30 and 31 with the bore 28 that receives the switchover valve 29. An actuation means 32, a spring device 33 and a control piston 34 of the switchover valve 29 are shown schematically in FIG. 1, and the function of these components of the switchover valve 29 is known from DE 10 2010 016 037 A1.
As described above, the hydraulic oil that acts on the pistons 20, 21 that are guided in the hydraulic chambers 22, 23 is fed to the hydraulic chambers 22, 23 from the crankpin bearing eye 11 via hydraulic lines 24 and 25. The connecting rod 10 is engaged by the crankpin bearing eye 11 on the crankshaft (not shown in FIG. 1) so that a crankshaft bearing journal of a connecting rod bearing shell 35 is arranged between the crankshaft and the crankpin bearing eye 11.
Hydraulic oil can be fed from the crankpin bearing eye 11 of the connecting rod 10 to the hydraulic chambers 22 and 23 via the hydraulic lines 24 and 25 that are integrated into the connecting rod 10 and is conducted in the direction of the crankpin bearing eye via first hydraulic lines integrated into the crankshaft. There is the risk of contaminants passing from the crankshaft into the hydraulic chambers, and thus into the connecting rod, via the hydraulic oil. These contaminants could impair the functioning of the check valves of the eccentric adjustment device and the switchover valve. In the extreme case, the eccentric adjustment device and the connecting rod may fail.
DE 101 08 461 B4 discloses a crankshaft bearing arrangement for an internal combustion engine having an adjustable compression ratio. The crankshaft bearing arrangement has the crankshaft mounted in eccentric rings, and an oil distribution groove is provided on the outer circumferential face of the eccentric ring. Oil can pass in the direction of the oil distribution groove via an oil feed channel in the engine housing.
It is an object of the invention to provide an improved internal combustion engine and an improved connecting rod.